We have talked about this extensively on the forums before (although it might have been over on IP); about clients in denial over their hearing loss.
This is a trap!
There is probably nothing wrong with the speakers, it is probably their hearing. And they will have you swapping speakers out till they have gone thru every brand and model on the planet.

As mentioned above, you need a DSP on this setup. Start with some compression, then some EQ: boosting the midrange and cutting some midbass.